The recent American Society of Civil Engineers report on the assessment of infrastructure condition resulted in an overall grade of D+, which is rather unsatisfactory. Long-term aging and deterioration of structures pose a significant threat to structural resiliency in the event of natural and man-made hazards. Reinforced concrete structures are difficult to model analytically because of interaction between concrete and reinforcing bars. Hence, the overarching goal of this project is to improve the capability of the engineering community to analyze reinforced concrete structures computationally by establishing a large-scale physics-based computational framework for the simulation of infrastructure. With accurate computational simulation models it would be possible to simulate deteriorating agents such as corrosion, cracks, chemical attack on concrete etc. This research will advance the understanding of failure mechanisms of aged concrete structures. The rigorous mathematical and computational developments involved in the research will provide an ideal training platform for graduate students and will bring opportunities for educational advancement in the civil engineering undergraduate curriculum.
Accurate analytical modeling of failure behavior of quasi-brittle materials and structures in presence of long-term deterioration is a complicated problem that is still unsolved. Reliable simulations require accurate descriptions of various meso-scale phenomena, which are not taken into account by available phenomenological computational models. Meso-scale (the scale of coarse aggregate particles in concrete) models capture these meso-scale features of failure but they are extremely intensive from a computational point of view. Based on a recently formulated discrete model called the Lattice Discrete Particle Model (LDPM), effective multi-scale techniques suitable for up-scaling discrete systems will be developed in this research. The main contribution of this project to the knowledge base will be the formulation and validation of a multi-scale framework for the simulation of reinforced concrete (1) accounting for the most common long-term deterioration mechanisms, e.g., freeze-thaw cycles, alkali-silica reaction, shrinkage and creep; (2) including a bond algorithm to couple the concrete model with steel reinforcing bars and their expansive effect associated with steel corrosion; and, finally, (3) featuring multiple scale algorithms for the simulation of reinforced concrete frames.
